. Bulletin - United States National Museum. Science. a Figure 22.—View of left humerus, USNM 11976, of Pelocetus calvertensis: a, external view; b, internal view; c, view of distal end. Abbrs.: h., head; , radial facet; , radial tuberosity; ; ulnar facet. the coracoid process is well developed. This condition can hardly be regarded as an anomaly since the acromion is lacking on both scapulae. Among Recent mysticetes, the humpback whale (Megaptera) lacks both the acromion and the coracoid processes. Unfortunately, the posterovertebral angle is missing on both the right and left scap
. Bulletin - United States National Museum. Science. a Figure 22.—View of left humerus, USNM 11976, of Pelocetus calvertensis: a, external view; b, internal view; c, view of distal end. Abbrs.: h., head; , radial facet; , radial tuberosity; ; ulnar facet. the coracoid process is well developed. This condition can hardly be regarded as an anomaly since the acromion is lacking on both scapulae. Among Recent mysticetes, the humpback whale (Megaptera) lacks both the acromion and the coracoid processes. Unfortunately, the posterovertebral angle is missing on both the right and left scapulae, but nevertheless the maximum anteroposterior diameter when complete must have exceeded 500 mm. The blade, which is noticeably thickened on its basal half, becomes progres- sively thinner toward the vertebral border. The glenoid cavity (fig. 21b) is deeply concave and meas- ures 110 mm. anteroposteriorly and 80 mm. exterointemally. The spine of the scapula seems to be represented by the prominent oblique dorsoventral ridge which fades into the outer surface above the coracoid process and disappears near but below the vertebral margin. The outer surface of the scapula is marked by three, possibly four, ridges that radiate upward from the depression above the glenoid border. The fingerlike attenuated coracoid process projects outward and slightly inward from the base of the scapula anteriorly above the glenoid border, and measures about 65 mm. in length, the free end being somewhat knoblike, and the inner surface slightly flattened. The prescapular fossa is relatively broad and flat, the maximum width being greater than 105 mm. The posterior margin of the scapula is concavely curved in contrast to the convex curvature of the anterior margin; the vertebral margin seems to have been somewhat convex and presumably was characterized by a cartilaginous condition similar to that of Recent mysticetes. Measurements (in mm.) of the scapula of USNM 11976 are as follows: Maximum ante
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